Method and apparatus for cementing wells



Dec 7y T5937.4 w. c. CHONETTE E-r AL 2,1GL640 y METHOD AND APPARATUS FORCEMENTING WELLS Filed Oct. 7, 1 .935 2 Sheets-Sheet l DHL 7, W37. W. c.CHONETTE Er Al. WLM@ METHOD AND APPARATUS FOR CEMENTING WELLS Filed Oct.7, 1955 2 Sheets-sheet 2 Patented Dec. 7, 1937 METHOD AND APPARATUS FORCEMENTmG WELLS William Cantwell Chouette, Cjai, and Robert H. lamilton,Los Angeles, Calif., asngnors to Shell Development Company, SanFrancisco, Calif., a corporation ci Delaware Application october i,i935. semi No. 4ans a emma (Ci. itt-2i) This invention relates to theart of cementirig oil wells and pertains more particularly to animproved method and apparatus for cementing oil wells fitted with linersor strings of casing 5 without removing the latter from the well.

During drilling operations, it often becomes necessary to place a cementplug opposite an interval that is, a certain vertical stretch of thewell where the well penetrates a formation ycontaining water, in orderto prevent the water from entering the well. In cases where an oilstring or pipe has not already been permanently set by cementing at alevel above the desired point, and it is possible to remove the stringof l5 casing before attempting to place the, cement plug, the operationis relatively simple and may easily be carried. out by available methodsand devices. However, in cases where a casing is to be cemented whichcannot be removed, or a per- 2o forated casing is used, considerable.dimculties are experienced in eiectively cementing' a well. Thus, it isknown to place a cement mixture inside a perforated pipe at the desiredpoint and to utilize the static pressure du'e to thedifference inspecific gravity .of the cement mixture. and of the well fluid presentin the borehole. The pressure developed by this method is, howeversometimes insuillcient to drive all of the cement charge through thecasing perforations, so asr to ll eilectively the space outside thecasing. It is also `known to utilize explosives to rupture the casing atthe vdesired point, thereby permitting the cement to how out of the pipeand to form a bond with the formation. This method is, however obviouslyexpensive and hazardous.

4 It is an object of this invention to provide a method and apparatuswhich overcomes the disadvantages of the present methods and equipmentby applying the positive mechanical pressure of the weight of part orall of a tubing string on top of a packer lowered lntothe casing toforce the cement slurry into the annular space between the casing andthe borehole.

It is a further object of this invention to provide i5 'a method andapparatus which could be used in cementlng bottom, intermediate and topmnes of oil wells provided with perforated casing.

It is another object of this invention to provide a method and apparatuswhich makes it possible `5I) to circulate mud iiuid in the well duringand after the cementlng operation, thereby effectively removing theexcess cement slurry from the tubing and casing.

I'he construction and operation of this cement- 55 ing device will beunderstood from the following description of a preferred embodiment,without, however, in any way limiting thereto the present invention,which consists broadly in running a packer or plunger body on a tubingstring into a cased well, anchoring it therein, introducing a cementmixture into the space below the packer.

and then applying the positive mechanical pressure of the weight ofpartor all of the tubing string to the top of the packer to force itdown, whereby the packer, acting as a plunger or piston, forces thecement slurry around the lower edge of the casing, or through theperforations in said casing, into the annular space between the walls ofthe borehole and the casing.

In the accompanying drawings: w

Figure 1 shows an elevation view, partlyin cross-section, of the packeror plunger body;

Figure 2 gives a'. detailed cross-sectional view ofthe upper part of thepacker or plunger body the tubing being shown withdrawn therefrom. 20

Figure 3 is a plan view of ligure 2.

Figures 4, 5, 6 and 7 diagrammatically show the relative positions ofthe packer or plunger body during the successive steps of the cementingprocess. 1 i

` Referring to Figure 1, a string ofcasing t, which may haveperforations t, is shown lowered into a. borehole t. The packer orplunger body is indicated ingeneral by the numeral It. VIt is loweredinto the borehole inside the casing at the 30 end of a. tubing string 2.The upper section I of the packer body I2, which may form an integralpart thereof, or may be rigidly connected thereto in any other manner,as, for example, by means of screw-threads' II, has a recess t adaptedto 35 receive lugs t, which are integral with the tubingstring i, being,for example, welded thereto. The packer body is rigidly connected to thetubing i by means of these lugs. However, as shown in Figures 2 and 3the lugs may be withdrawn from re- 40 cess t through vertical slots 5Aby rotating the tubing 2, and thereby disconnecting itfrom the packerbody. The section I has in its lower part a recess It wherein aflap-valve 9 is mounted on an axis I3. This flap-valve is under thepressure y of a spring I i, and automatically closes the recess I3 assoon as the tubing 2 is Withdrawn from the packer body. The section Ihas also an outside opening 1 through which the flap-valve may be raisedand set whenthe device is being prepared for operation. The packingproper is shown as consisting of alternating rings of wood I9 and ofleather 2 I, although it may be constructed in any other suitablemanner, and any other fibrous, plastic or semi-plastic material may beused, such,

for example, as rubber, rubberized canvas, brass, bronze, etc. The ringsI@ and ii are iirmly held between the upper section i and a steel ring23 screwed on the mandrel of the packer bo'dy I2. Automatic slips I4 aremounted on the packer body I2 below the packing, and are actuated by atripping mechanism to expand and firmly grip the casing 6 when thetubing 2 is rotated in a direction opposite to that which is used todisengage lugs 3 from the recess b. The construction of the slips I4 andof the tripping mechanism 25 is conventional, and forms no part of thisinvention; it is recited here only inasmuch as it is necessary for theoperation of the present invention. Guides It may be provided on thelower part of the packer body I2. A portion 2l of the tubing 2 extendsbelow the packer body, and is provided with holes 29, through which thecement slurry or the mud duid may be circulated. This portion 21 ispreferably, but not necessarily, externally flush jointed in order thatit may pass freely through the recess it.

The operation of the device will be understood from the followingdescription, taken with reference to Figures 4, 5, 6 and 7, whichillustrate the various steps of the present procesa The oil well casingis rst cleaned throughout its length from the surface to the bottom ofthe interval where it is desired to effect the cementing, theperforations of the casing being, if desired, washed. The packer body is`then lowered to the desired depth at the end of a string oi tubing,with the slips it locked in a contracted position and the iap valve 9held open by the tubing 2, as shown in Figure i. The length of thetubing 21 is preferably arranged so that when it touches the bottom cithe borehole, the packer rings I9 and 2i lare slightly above the top oithe interval where the ementing is to be effected. It it is desired tocement the borehole opposite an interval which is not adjacent to thebottom thereof, but lies in some intermediate or top zone, an ordinaryplug made of wood, leather, rubber, canvas, etc., may be iirst set inthe casing at the desired point, whereupon the device of the presentinvention is lowered until the tubing 2l! touches said plug, or lies inclose proximity thereto.

When the device has assumed its correct position in the borehole, theslips I4 are set by rotating the tubing in one direction, for example,to the left, and slightly pulling the tubing up. The tubing is thenreleased from the packer body, but not withdrawn therefrom, by rotatingit in the opposite direction, for example, to the right, which frees thelugs 3 from the recess B, as shown in Figure 5. The circulation of thefluid through the tubing is then established, and the required amount ofcement slurry pumped into the bottom of the perforated pipe, or on topof the plug if the cementing is being eiiected man intermediate or topzone. The upper level oi the cement should preferably be Just below thepacker body when the raised with the' tubing during this operation.'

Mud iiuid Is then circulated through the tubing on top oi the packerbody to prevent any cement from remaining within the tubing orperforated casing above the packer. While themud iiuid is beingcirculated, the tubing is again lowered and the pressure due to part orall of its weight is aparenoso plied to the top of the packer body,closed by iiap valve il. This pressure releases the slips I 4 and movesthe packer body down the casing. The piston or plunger action of thepacker body forces the cement slurry around the lower edge of the casingor through the perforations in the casing into the annular space betweenthe casing and the borehole, as shown in Figure 7, thus eiectivelycementing the well. Any cement slurry leaking through the packing ringsI8 and I9 or passing back into the casing through its perforations abovethe packer is removed to the surface by the circulating mud or otherfluid, whereby the possibility of cementing the tubing or of bridgingthe casing is eliminated. When the cement has set, the packer remainscemented in the casing, and as it is preferably constructed of suchmaterials as cast iron, bronze, leather, rubber, wood, etc., it may be,if required, easily drilled out during subsequent operations.

The terms tubing and tubing string used herein are to be construed in abroad sense to mean any hollow tube lowered into a borehole such as oilwell tubing, oil well casing, drill pipe, line pipe, etc.

We claim as our invention:

l. In the process of Vcementing wells provided with casing, the steps oflowering thereinto a packer body detachably attached to a. tubingstringextending through the packer body, anchoring said body within the casingagainst upward motion, placing a iiuid cementing mixture below thepacker body withdrawing the tubing from the packer body, closing thebore in the packer body, and applying the mechanical pressure of thetubing string to the top of the packer body, said pressure beingsuiiicient to move the packer body downward and to force the cementingmixture below the packer body into the space between the walls of theborehole and the casing.

2. In the process of cementing wells provided with perforated casing,the steps of lowering thereinto a packer body detachably attached to atubing string extending through the packer body, anchoring said bodywithin the perforated casing against upward motion, placing a fluidcementing mixture below the packer body withdrawing the tubing from thepacker body, closing the bore in the packer body, and applying themechanical pressure of the tubing to the top oi' the packer body, saidpressure being suiiicient to move the packer body downward and to forcethe cementing mixture below the packer body through the perforations inthe casing into the space between the walls of the borehole and thecasing.

3. In the process oi' cementing wells provided with casing, the steps oflowering thereinto a packer body detachably attached to a tubing stringpassing through a. bore in said body, anchoring said body within thecasing against upward motion, placing a cementing mixture through thetubing into the space below the packer body, withdrawing the tubing fromthe packer body, closing the bore in the packer body, and circulating aiiuid mixture in the tubing and the casing above the packer body whileapplying the mechanical pressure of the tubing string to the top oi' thepacker body, said pressure being suicient to move the packer bodydownward and to force the cementing mixture below the packer body intothe space between the walls ot the borehole and the casing.

. 4. In the process oi' cementing wells provided arancio with perforatedcasing, the steps of anchoring a plug in the casing near the bottom l of`the interval where the cementing is to be eiIected, lowering lnto thewell a packer body detachably attached to a tubing string passing'through a bore in said body, anchoring the packer-in the casing at apoint above the plug.. placing a oementing mixture through the tubinginto the space between the plug and the packer body, withdrawing thetubing from the'pacler body, closing the bore in the packer body, andcirculating a-uid mixture in the tubing and the casing above the packerbody while applying the mechanical pressure of the tubing string tothetop or the' 'packer body. said pressure being. sufcient to move thepacker body downward and to force the oementing miuture between thepacker body and the plug into the space between the walls of the borehole and the casing through the periorations in said casing. 1

5. A device for cementing wells provided'with casing, comprising astring of tubing, an elongated cylindrical packer body, a vertical borethrough the packer body, 'said boreproviding an unobstructed passage forsaid tubing, means linitary with the tubing for discharging a duid intothe casing below said packer body, means detachably attaching the packerbody to the tub ing, means on theA packer body adapted for grippingengagement with the casing. means ior disconnecting and withdrawing thetubing together with the fluid discharge means from the packer body, anda valve adapted to close the vertical bore in the packer body when thetubing is withdrawn therefrom.

6. A device for cementing wells provided with.v

casing, `comprising a string of tubing. an elongated cylindrical packerbody, a vertical bore through the packer body, said bore providing an.unobstructed passage i'or said tubing, means unitary with the tubing fordischarging a iiuid into the casing' below said packer body, meansdetachably attaching the packer body to the tubing, means on the packerbody adapted for gripping engagement with the casing, means iordisconnecting and withdrawing the tubing together with the fluiddischarge means from the packer body, and means to apply the downwardpressure of the tubing string to the top of the packer body.

7. A device for cementing wells providedvwith casing, comprising astring of tubing, an elongatedv cylindrical packer body, a vertical borethrough the packer body, said bore providing an unobstructed passage forsaid tubing, means unitary with the tubing for discharging a iiuid intothe casing below said packer body, means detachably attaching the packerbody to the tubing, means on the packer body adapted for grippingengagement with the casing, means for disconnecting and withdrawing thetubing together with the iluid discharge means from the packer body, andmeans to apply the downward pressure of the tubing string to the top oithe packer body, said last means comprising a valve adapted to" closethe vertical bore in the packer body when the tubing is withdrawntherefrom.

8. A device for cementing wells provided with casing, comprising astring of tubing, an elongated cylindrical packer body, a vertical borethrough the packer body, Asaid 'bore providing an unobstructed passagefor said tubing, means unitary with the tubing for discharging a fluidinto the casing below said packer body, means detachably attaching thepacker body to the tubing, means on the packer body adapted for grippingengagement with the casing, means for disconnecting and withdrawing thetubing together with the fluid discharge means from the packer body, andmeans to apply the downward pressure of the tubing string to the top ofthe packer body,

l said packer body-being made of a material adapted to4 be drilled outof the borehole.

9. In the'process of cementing wells provided with casing, the steps oflowering thereintoa packer body detachably attached to a tubing stringextending through said packer body, an-

lchoring said packer. body within the casing against upward motion,placing through` the tubing a cementing mixture below the packer body,withdrawing the tubing from the packer body, closing the bore in thepacker body, circulating a Huid mixture in the tubing and casing abovethe packer while applying a mechanical pressure and drilling throughsaid cement plug.

. t' i.: cHoNnT'rn.

ROBERT H. 1"; v

TON.

